In some types of partial middle ear implantable (P-MEI) or total middle ear implantable (T-MEI) hearing aid systems, piezoelectric transducers are used in which sounds produce mechanical vibrations which are transduced by an electromechanical input transducer into electrical signals. These electrical signals are in turn amplified and applied to an electromechanical output transducer. The electromechanical output transducer vibrates an ossicular bone in response to the applied amplified electrical signals to improve hearing.
Because of the transducers location, they need to be protected from the ambient environment. In particular, the transducers need to provide moisture, microbial and tissue adhesion resistance. In addition, they need to be biocompatible. Also, the protection provided must have a low spring rate and low mass loading to not interfere with the operation of the transducer and to minimize vibrational transmission losses to the middle ear ossicles.